A Review of the Calcium Sulphoaluminate Cement Mixed with Seawater: Hydration Process, Microstructure, and Durability

The preparation of low-cost and high-durability cement-based material systems using seawater mixing has become an urgent task in marine engineering construction. The requirements have addressed key challenges, including high transportation costs for fresh water and raw materials, poor structural durability, and difficulty in meeting actual construction schedules. Sulfatealuminate cement (CSA) has become an ideal material for marine engineering due to its high corrosion resistance, rapid early strength, which is 35–40 MPa of 3-day compressive strength and is 1.5–2 times compared ordinary Portland cement (OPC), and low-carbon characteristics, reduced production energy consumption by 35–50%, and CO₂ emissions of 0.35–0.45 tons/ton. The Cl⁻ and SO₄²⁻ in seawater can accelerate the hydration of CSA, promote the formation of ettringite (AFt), and generate Friedel’s salt fixed chloride ions, significantly enhancing its resistance to chloride corrosion. Its low alkalinity (pH ≈ 10.6) and dense structure further optimize its resistance to sulfate corrosion. In terms of environmental benefits, CSA-mixed seawater can save 15–20% fresh water. And the use of solid waste preparation can reduce environmental burden by 38.62%. In the future, it is necessary to combine multi-scale simulation to predict long-term performance, develop self-healing materials and intelligent control technologies, and promote their large-scale application in sustainable marine infrastructure.